A RDM Transceiver
Qualification Tester

from Goddard Design

Your DMX512 & RDM Test Tools
Source

Goddard Design is proud to introduce an
important test tool for
anyone
designing or verifying a new E1.20 (RDM) design. Our RDM Driver
Qualification Test Set simplifies the required driver tests.

If you are designing an RDM device, the selection of the line driver is
not as simple as it once was. Just because an integrated circuit is
labeled as a EIA485 driver does not mean that it is appropriate for RDM
use. Electrical requirements have been added to increase the
reliability of the protocol. For the purposes of E1.20 (RDM) the line
transceiver IC and any bias components are jointly considered to be the
line driver, and together must be qualified to drive the EIA485/E1.20
line. From the standard:

“2.4
Maintaining data link state between packets
. . . Typically, there may be considerable time when all transmitters
are in a high impedance state. It is imperative that the data link
shall maintain a marking state between packets, even if all
transmitters are disabled.” . . .
“The command port shall provide a means to bias the termination of the
data link to a value of at least 245 mV and
verified by using the test circuit described in Appendix F.”

Because schemes providing this bias place an additional electrical load
on transmitters, all controller and responder transceiver designs must
be tested for conformance. While these tests are simple, construction
and verification of a test set can be time consuming and
expensive.

Goddard Design now offers a three PCB set that allows any EIA driver
and biasing scheme to be tested to the requirements of Appendix F in a
matter of minutes.
The test set includes:

A standard test load card that implements the four
required tests

Two DUT test cards that take a standard 485 transceiver in
an 8 pin DIP package. An adapter to SO8 or SOP8 packages is available.
One card comes with the E1.20 default bias network installed, the other
card is left open for user designs.

Three universal switching powers supplies are included.

All the user needs to provide is one adjustable bench power
supply capable of supplying the DUT, and a good quality DVM.

You may a download
the print version of this data sheet. (5.16M)This
file is in PDF format. You will need a PDF viewer to read and print it.
If you do not have one it may be downloaded for free from
Adobe.Goddard
Design Company51
Nassau Ave.Brooklyn
NY 11222 USA718
599-0170
718 599-0172 faxhttp://www.goddarddesign.com